Light emitting device and method of fabricating the same

ABSTRACT

Provided are a light emitting device and a method of fabricating the same. The light emitting device comprises: a first conductive semiconductor layer; an active layer comprising an InGaN well layer and a GaN barrier layer on the first conductive semiconductor layer; and a second conductive semiconductor layer on the active layer. The GaN barrier layer comprises an AlGaN layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a 37 C.F.R. §1.53(b) continuation ofco-pending U.S. patent application Ser. No. 12/145,320 filed Jun. 24,2008, which claims priority on Korean Patent Application No.10-2007-0062005, filed on Jun. 25, 2007. The entire contents of all ofthe above applications are hereby incorporated by reference.

BACKGROUND

Embodiments relate to a light emitting device and a method offabricating the same.

A light emitting diode is generally used as a light emitting device.

In the light emitting diode, an N-type semiconductor layer, an activelayer, and a P-type semiconductor layer are stacked. Thus, light isgenerated in the active layer and then is emitted to the outsideaccording to applied power supply.

SUMMARY

Embodiments provide a light emitting device and a method of fabricatingthe same.

Embodiments also provide a light emitting device with improved lightemitting efficiency and electrical characteristic and a method offabricating the same.

In an embodiment, a light emitting device comprises: a first conductivesemiconductor layer; an active layer on the first conductivesemiconductor layer; and a second conductive semiconductor layer on theactive layer. The active layer comprises an InGaN well layer, a firstGaN barrier layer on the InGaN well layer, an AlGaN layer on the firstGaN barrier layer, and a second GaN barrier layer on the AlGaN layer.

In an embodiment, a light emitting device comprises: a first conductivesemiconductor layer; an active layer comprising an InGaN well layer anda GaN barrier layer on the first conductive semiconductor layer; and asecond conductive semiconductor layer on the active layer. The GaNbarrier layer comprises an AlGaN layer.

In an embodiment, a method of fabricating a light emitting devicecomprises: forming a first conductive semiconductor layer; forming anactive layer on the first conductive semiconductor layer; and forming asecond conductive semiconductor layer on the active layer. The formingof the active layer comprises: forming an InGaN well layer on the firstconductive semiconductor layer; forming a first GaN barrier layer on theInGaN well layer; forming an AlGaN layer on the first GaN barrier layer;and forming a second GaN barrier layer on the AlGaN layer.

The details of one or more embodiments are set forth in the accompanyingdrawings and the description below. Other features will be apparent fromthe description and drawings, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a light emitting device according toa first embodiment.

FIG. 2 is a cross-sectional view of a light emitting device according toa second embodiment.

FIGS. 3 to 8 are cross-sectional views illustrating a method offabricating a light emitting device according to an embodiment.

FIG. 9 is a graph illustrating temperature change and injection gasduring the forming of an active layer in a method of fabricating a lightemitting device according to an embodiment.

DETAILED DESCRIPTION OF THE EMBODIMENTS

In the following description, it will be understood that when a layer(or film) is referred to as being ‘on/under’ another layer or substrate,it can be directly on/under the another layer or substrate, orintervening layers may also be present.

Hereinafter, a light emitting device and a method of fabricating thesame will be described with reference to the accompanying drawings.

FIG. 1 is a cross-sectional view of a light emitting device according toa first embodiment.

Referring to FIG. 1, the light emitting device of the present inventionincludes a substrate 10, a buffer layer 20 formed on the substrate 10,an un-doped GaN layer 30 formed on the buffer layer 20, a firstconductive semiconductor layer 40 formed on the un-doped GaN layer 30,an active layer 50 formed on the first conductive semiconductor layer40, a second conductive semiconductor layer 60 formed on the activelayer 50, and a first electrode layer 70 and a second electrode layer 80formed on the first conductive semiconductor layer 40 and the secondconductive semiconductor layer 60, respectively.

Additionally, the active layer 50 includes an InGaN well layer 51, afirst GaN barrier layer 52 formed on the InGaN well layer 51, an AlGaNlayer 53 formed on the first GaN barrier layer 52, and a second GaNbarrier layer 54 formed on the AlGaN layer 53.

The AlGaN layer 53 may grow with a thickness of one to three monolayers. That is, the AlGaN layer 53 may grow with a thickness of 5.18 Åto 15.54 Å.

In the light emitting device of the first embodiment, the active layer50 is used for preventing a leakage current and forming a high qualitybarrier layer through the AlGaN layer 53 between the first GaN barrierlayer 52 and the second GaN barrier layer 54.

Especially, the second GaN barrier layer 54 is formed at a temperatureof 850° C. to 1100° C., which is higher than a temperature at which thefirst GaN barrier layer 52 is formed.

Accordingly, the second GaN barrier layer 54 may be formed of a highquality thin layer and a pit causing a leakage current may be removed,such that electrical characteristics can be improved.

FIG. 2 is a cross-sectional view of a light emitting device according toa second embodiment.

Referring to FIG. 2, only the different contents between FIG. 2 and FIG.1 will be described.

In the light limiting device of the second embodiment, an active layer50 includes an InGaN well layer 51, a first GaN barrier layer 52 formedon the InGaN well layer 51, an AlGaN layer 53 formed on the first GaNbarrier layer 52, and a second GaN barrier layer 54 formed on the AlGaNlayer 53, all of which constitute one period.

Moreover, the active layer 50 includes an InGaN well layer 55 formed onthe second GaN barrier layer 54, a first GaN barrier layer 56 formed onthe InGaN well layer 55, an AlGaN layer 57 formed on the first GaNbarrier layer 56, and a second GaN barrier layer 58 formed on the AlGaNlayer 57, all of which constitute another period.

Although not illustrated, the active layer 50 includes a plurality ofperiods, such that a plurality of well layers, first barrier layers,AlGaN layers, and second barrier layers can be repeatedly formed.

That is, the active layer 50 may have a multi quantum well structure.

FIGS. 3 to 8 are cross-sectional views illustrating a method offabricating a light emitting device according to an embodiment.

Referring to FIG. 3, a substrate 10 is prepared, and then a buffer layer20, an un-doped GaN layer 30, a first conductive semiconductor layer 40,and an InGaN well layer 51 are sequentially formed on the substrate 10.

The substrate 10 may be formed of at least one of sapphire (Al2O3), Si,SiC, GaAs, ZnO, or MgO, and the buffer layer 20 may be formed of atleast one of an AlInN/GaN multilayer structure, an InxGa1-xN/GaNmultilayer structure, or an AlxInyGa1-(x+y)N/InxGa1-xN/GaN multilayerstructure.

The un-doped GaN layer 30 is formed with a supply of TMGa and NH3. Atthis point, N2 and H2 may be used as a purge gas and a carrier gas.

The first conductive semiconductor layer 40 may be formed of a Si—Inco-doped GaN layer doped with silicon and indium simultaneously, and isan N-type semiconductor layer.

The InGaN well layer 51 is formed with a supply of NH3, TMGa, and TMInat a temperature of 650° C. to 850° C. In the embodiment of FIG. 9, theInGaN well layer 51 is formed at a temperature of 700° C.

Referring to FIG. 4, the first GaN barrier layer 52 is formed on theInGaN well layer 51.

After the forming the InGaN well layer 51, the first GaN barrier layer52 is formed with a supply of NH3 and TMGa at a temperature of 800° C.to 1000° C. by drastically increasing a temperature by 150° C. with aratio of 2° C./sec. In the embodiment of FIG. 9, the first GaN barrierlayer 52 is formed by increasing temperature from 700° C. to 850° C.

Referring to FIG. 5, an AlGaN layer 53 is formed on the first GaNbarrier layer 52.

The AlGaN layer 53 is formed with a supply of NH3, TMGa, and TMAl at atemperature of 800° C. to 1000° C. The AlGaN layer 53 may grow with athickness of 5.18 Å to 15.54 Å. In the embodiment of FIG. 9, the AlGaNlayer 53 is formed at a temperature of 850 Å.

Referring to FIG. 6, a second GaN barrier layer 54 is formed on theAlGaN layer 53.

After the forming the AlGaN layer 53, the second GaN barrier layer 54 isformed with a supply of NH3 and TMGa at a temperature of 850° C. to1100° C. by drastically increasing temperature by about 150° C. at aratio of 2° C./sec. In an embodiment of FIG. 9, the second GaN barrierlayer 54 is formed by increasing temperature from 850° C. to 1000° C.

The AlGaN layer 53 has durability against high temperature. Accordingly,the second GaN barrier layer 54 can be formed at a temperature that ishigher than a temperature at which the first GaN barrier layer 52 isformed. Accordingly, the quality of the second GaN barrier layer 54 canbe improved such that pits (which may be formed on the second GaNbarrier layer 54) are decreases.

The AlGaN layer 53 includes Al of 10% to 50%. That is, the AlGaN layer53 may be expressed as AlxGa1-xN (0.1≦×≦0.5).

On the other hand, the NH3 and TMGa are continuously supplied to protectthe surface of the InGaN well layer 51 during the forming of an activelayer 50 of FIG. 7.

Referring to FIG. 7, a second conductive semiconductor layer 60 isformed on the second GaN barrier layer 54.

The second conductive semiconductor layer 60 may be formed of a GaNlayer doped with Mg, and is a P-type semiconductor layer.

Referring to FIG. 8, the second conductive semiconductor layer 60, theactive layer 50, and the first conductive semiconductor layer 40 arepartially removed.

Furthermore, a first electrode layer 70 is formed on the firstconductive semiconductor layer 40, and a second electrode layer 80 isformed on the second conductive semiconductor layer 60.

In the above light emitting device, the active layer emits light whenpower supply is applied to the first electrode layer 70 and the secondelectrode layer 80.

On the other hand, the light emitting device of the embodiment includesthe active layer 50 having a structure of the InGaN well layer 51, thefirst GaN barrier layer 52, the AlGaN layer 53, and the second GANbarrier layer 54. Additionally, since the quality of the second GaNbarrier layer is excellent, electrostatic discharge (ESD) and breakdownvoltage characteristics are outstanding.

Embodiments provide a light emitting device and a method of fabricatingthe same. Furthermore, provided is a light emitting device with improvedlight emitting efficiency and electrical characteristics and a method offabricating the same.

Although a lateral type light emitting device (in which two electrodesare arranged in the top direction of a semiconductor layer) is describedin the above embodiments, the embodiments may be applied to a verticaltype light emitting device (in which two electrodes are disposed at thetop and bottom directions of a semiconductor layer).

Any reference in this specification to “one embodiment,” “anembodiment,” “example embodiment,” etc., means that a particularfeature, structure, or characteristic described in connection with theembodiment is included in at least one embodiment of the invention. Theappearances of such phrases in various places in the specification arenot necessarily all referring to the same embodiment. Further, when aparticular feature, structure, or characteristic is described inconnection with any embodiment, it is submitted that it is within thepurview of one skilled in the art to effect such feature, structure, orcharacteristic in connection with other ones of the embodiments.

Although embodiments have been described with reference to a number ofillustrative embodiments thereof, it should be understood that numerousother modifications and embodiments can be devised by those skilled inthe art that will fall within the spirit and scope of the principles ofthis disclosure. More particularly, various variations and modificationsare possible in the component parts and/or arrangements of the subjectcombination arrangement within the scope of the disclosure, the drawingsand the appended claims. In addition to variations and modifications inthe component parts and/or arrangements, alternative uses will also beapparent to those skilled in the art.

1. A light emitting device comprising: a first conductive semiconductorlayer; an active layer on the first conductive semiconductor layer; anda second conductive semiconductor layer on the active layer, wherein theactive layer comprises a plurality of structures including an InGaN welllayer, a first GaN barrier layer on the InGaN well layer, an AlGaN layeron the first GaN barrier layer, and a second GaN barrier layer on theAlGaN layer, and wherein the second GaN barrier layer has less pits thanthe first GaN barrier layer thereof.
 2. The light emitting deviceaccording to claim 1, wherein the AlGaN layer is directly inter disposedbetween the first GaN barrier layer and the second GaN barrier layer. 3.The light emitting device according to claim 1, wherein the AlGaN layeris thicker than the first GaN barrier layer.
 4. The light emittingdevice according to claim 1, wherein the AlGaN layer is thicker than thesecond GaN barrier layer.
 5. The light emitting device according toclaim 1, wherein the AlGaN layer is thicker than both the first GaNbarrier layer and the second GaN barrier layer.
 6. The light emittingdevice according to claim 1, wherein each of the plurality of structureshas sequentially and directly stacked the InGaN well layer, the firstGaN barrier layer, the AlGaN layer, and the second GaN barrier layer. 7.The light emitting device according to claim 1, wherein the AlGaN layeris formed with a thickness of 5.18 Å to 15.54 Å.
 8. The light emittingdevice according to claim 1, wherein the AlGaN layer has a thickness ofone to three mono layers.
 9. The light emitting device according toclaim 1, wherein the AlGaN layer is expressed as Al_(x)Ga_(1-x)N(0.1≦×≦0.5).
 10. The light emitting device according to claim 1, whereinthe AlGaN layer is formed in the GaN barrier layer, and a top and abottom of the AlGaN layer directly contact the second and first portionsof the GaN barrier layer, respectively.
 11. The light emitting deviceaccording to claim 1, wherein the AlGaN layer is formed by directlycontacting the first GaN barrier layer.
 12. The light emitting deviceaccording to claim 1, wherein the second GaN barrier layer is formed bydirectly contacting the AlGaN layer.